In this paper a survey of metastabilities will be presented, which often occur in important technical materials and processes. Several metastable phases are formed during rapid cooling of liquids or solid precursors. The industrially applied mechanical alloying, leading to the formation of nano-crystalline and amorphous systems will be also treated briefly together with the metastabilities, associated with the high specific surfaces. This knowledge is useful in the appreciation of driving force of sintering process. Finally some harmful and beneficial manifestation of mechanically induced dislocation pileup will be outlined. They were observed in rolling contact or sliding friction in certain mechanical machine parts.

Structural transformations that are taking place in metallic glasses have severe impact upon their performance in variety of practical applications. Their originally amorphous structure changes under elevated temperature. Eventually, partial crystallization occurs. In order to follow the development of crystallization, the investigation of heat treatment of Fe-based metallic glasses was performed. Modifications in structure were studied by employing in-situ techniques of synchrotron radiation. Namely, diffraction experiments and nuclear forward scattering of synchrotron radiation are reported. Both methods of study were performed on-fly providing information about the state of the samples in real time.

The methods of acoustic spectroscopy are powerful tool for the study of physical properties of condensed matter containing nanostructures. The ability of these methods makes it possible to obtain important information for variety of materials concerning not only their mechanical properties. The principles of acoustic spectroscopy of some kinds of materials and structures as results of a interaction between the acoustic wave and charge curriers and/or nanoparticles are presented. Semiconductor structures and magnetic fluids are the representative selection of condensed matter manifested the convenience of acoustic spectroscopy methods to obtain some physical parameters of nanostructures.

We have performed noise spectroscopy and charge transport properties analysis of CdTe detectors. Two types of high volume detectors are compared: Low-ohmic (based on low-resistivity crystal material ρ = 70 Ωcm) and semi-insulating (ρ = 108 Ωcm).The theoretical fundaments of contacts role in detector system are given. We observed high asymmetry of IV characteristics of the lowohmic sample between “normal” and “reverse” bias, showing improper quality of contacts preparation, caused by higher concentration of impurities in metal-semiconductor area. This finding is supported by the fact that the low frequency noise spectral density is proportional to applied voltage with exponent 2.7, which is higher than the theoretical value 2.The semi-insulating sample very good contact rectification effect symmetry and less additive noise to the detector system.

Although hydrogenated amorphous silicon has its important practical application there still is not any generally accepted model explaining all the physical phenomena on-going in this matter. The aim of this paper is to familiarize the reader with a model allowing to explain the empirically observed compensation effect (Meyer-Neldel rule – MNR). This effect reflects the correlation between activation energy and pre-exponential factor in relation to the activation dependence of electrical conductivity of semiconductors, including a-Si:H. The model assumes that the recombination of carriers is conditioned by emission of series of monoenergetic phonons. The number of emitted phonons is dependent on the activation energy of disordered semiconductor, which influences the probability of recombination and thus the concentration of free electrons. Consideration of the relationship between compensation effect and Urbach rule is also presented.

Organic molecules possessing a π-conjugated (hetero)aromatic backbone are capable of transporting charge and interact efficiently with light. Therefore, these systems can act as semiconductors in opto-electronic devices similar to inorganic materials. However, organic chemistry offers tools for tailoring materials’ functional properties via modifications of the molecular units, opening new possibilities for inexpensive device manufacturing. In this presentation, we discuss exploitation of such organic molecular systems in photovoltaics; the operation, advantages, and limitations of molecular donor-acceptor heterojunction structures.

The results of experimental investigation of the impact of ambient surroundings on refractive index inhomogeneity induced in LiNbO3:Fe:Mn crystal are presented in the article. The effect of dielectric (ambient air, paraffin oil) and electrically conducting (saturated aqueous solution of CaCl2) media surrounding the sample was investigated. The refractive index inhomogeneity in the sample was created due to photorefractive effect and monitored in real time by means of Mach-Zehnder interferometer. The time dependences of the amplitude of the induced refractive index changes were obtained from captured interferograms. The analysis of the obtained time dependences shows that the temporal behaviour of the inhomogeneity during and after its formation as well as the spatial distribution of the refractive index within the inhomogeneity depends significantly on electric properties of a medium surrounding the crystal sample.

Ag based alloys are widely used in the modern brazing technologies for the substitution of tin-lead based alloys. In the present work the wetting ability between graphite substrate and diluted Ag-M (M: Cd, In, Sn, Sb) has been studied using the sessile drop method. The contact angle between the liquids and solid substrate was measured at 1200˚C. Subsequently the micro structure of the solidified drops was investigated applying X-ray diffraction (XRD) and transmission electron microscopic (TEM) measurements. A texture formation was found in the substrate/drop interface region. Comparing the values of the contact angles measured on the Ag- M samples with the degree of the texture determined by XRD it was found, that the contact angle is smaller the degree of texture higher.

The continuing interest in development of new soft magnetic alloys is driven by industrial need to enhance the performance of electrical power generation/distribution devices and various energy conversion and sensor systems. In this work we report on development of Fe-Co-B-(P)-Cu melt-spun alloys with high magnetic flux density, where the beneficial effects of a heat treatment under magnetic field are discussed in terms of the improved magnetic softness and the possibility to tune the application-oriented properties. Soft magnetic FeNi- and FeCo-based amorphous and nanocrystalline alloys attract a considerable attention for various magnetic sensors. Examples of our recent work on the utilization of both longitudinal and transverse magnetic field annealing for tuning of giant magnetoimpedance (GMI) response in these alloys are briefly presented. The last part of this paper is devoted to search for magnetic materials with suitable magnetocaloric properties for magnetic refrigeration technology. We report on the beneficial effect of a partial cobalt substitution for iron on the magnetic entropy characteristics and the enhancement of refrigerant capacity in GdFe(Co)Al-based alloys.

Ferromagnetic amorphous glass-coated microwires are progressive materials that exhibit very useful behaviour, like the giant magnetoimpedance (GMI) effect, which is the base the operating principles for different magnetic sensors. In order to obtain large GMI values, it is necessary to choose the optimal chemical composition of the wire material with large permeability and small penetration depth. Aim this work is study of the magnetic properties of Co70,5Fe4,5Si15B10 alloys for GMI sensor application. Low prices and high flexibility of GMI sensors will warrant wide-ranging application in the near future.

The giant magnetoimpedance (GMI) dependence on the external magnetic field strength H in as cast Co70.5Fe4.5Si15B10 amorphous microwire exhibits double-peak behaviour. The position of sharp peaks is symmetrical with respect to zero external magnetic fields strength H=0 and corresponds to the critical field strength H=±Hm . The maximum GMI ratio (ΔZ/Z)max dependence on the amplitude iac is analysed by means of the helical anisotropy (0< a < 90o). The additional dc bias current idc in the interval from 0 to 0.25 mA with iac=0.1 mA was applied in order to observe the asymmetric GMI effect. The hysteresis in asymmetric GMI(H) dependences is explained by an irreversible magnetization rotation.

A simple analytically solvable model for description of dynamics of the domain wall depinning process from the closure domain structure in bistable microwires was proposed. In this model closure domain structure is modelled by a single domain wall located in quadratic potential well. Critical parameters of rectangular magnetic field pulse needed to release this wall from the potential well were calculated. Theoretical dependence obtained in this way was fitted to experimental data measured on glass-coated Fe77.5B15Si7.5 microwire. Information about the order of closure domain structure dimension and about the mass of the domain wall, which is depinned from the wire end were obtained in this way.

The magnetization processes in amorphous ferromagnetic alloys were studied by the hyperbolic model of hysteresis. The measured hysteresis data were used for separation of the domain wall movement, domain rotation and domain wall annihilation and nucleation process during decreasing of the excitation magnetic field. The external applied tensile stress was used as a parameter. Our results show that the process of the domain rotation is the most sensitive for the applied stress. The corresponding magnetization energy decreases with increasing of the mechanical stress for all our studied samples with the positive magnetostriction coefficient.

The paper deals with the study of strain distribution in hydrogenated FeB ribbons prepared by rapid quenching from the melt. Hydrogen atoms introduced during the process of hydrogenation induce internal stresses in the sample. This causes bending of a one side hydrogenated non-fixed ribbon. The ribbon bending reflects hydrogen concentration. When the ribbon is dehydrogenated the ribbon shape is fully restored for the studied Fe85B15 sample. A simple theoretical model is proposed to describe dependence of ribbon bending on the hydrogen concentration during process of hydrogenation as well as in the process of spontaneous dehydrogenation. A proposed theoretical model is in a good agreement with experimental results. Its fitting to experimental data provides important information on the local enlargement of the space around introduced hydrogen atoms.

The thermopower (S) measurement is proposed as an acceptable method after a suitable calibration for the study of compositional and structural (phase related) factors, to determine a level of heat treating or even the level of internal stress state in engineering alloys. We are focusing on to determine the influence of various Ni content in FeNi alloy system both in amorpus and in crystalline state. We also define the influence of mechanical and surface stress from the point of view of thermopower. The results of thermoelectric power measurements reported in this paper do confirm the applicability of S (T) measurements in the determination of compositional effects and mapping the stress state in different type of engineering alloys.

Different mechanisms of grain growth processes in grain-oriented (GO) steels are discussed. It has been shown that, application of particular thermomechanical treatment conditions leads to an appropriate microstructure and texture state in the investigated electrical steel. Short time annealing of the GO steel taken after final cold rolling reduction, at appropriate temperature leads to abnormal grain growth in the investigated steel. In this case, the Goss texture ({110}<001>) is the major texture component in the treated samples. Combination of temper rolling with appropriative annealing conditions leads to columnar grain growth development in the investigated GO steel.

Reduction of Si percentage in Fe-Nb-Cu-B-Si alloys known as Finemets results in 1.5 T saturation, surpassing so the standard Sirich compositions. However the other soft-magnetic properties are worse due mainly to magnetostriction and the consequences of socalled macroscopic heterogeneity. Therefore phosphorus has been added to the detriment of boron to test, whether this could be the way to suppress the undesired properties of Si-poor Finemets. Phosphorus appears to reduce the vulnerability of the ribbon surfaces to environmental influences at non-vacuum annealing and improves parameters like coercivity and magnetic anisotropy. Crystallization kinetics character remains preserved and critical temperatures change only negligibly.

Soft magnetic materials play an important role in broad applications, such as transformers and electrical motors. There is an interest in bulk soft magnetic materials because of the demand for miniaturization of cores. We have prepared bulk samples in the form of the small cylinders with good soft magnetic properties. The frequency dependence of magnetic properties is studied, and it is attributed mainly to the structure of the initial powder and domain wall damping. The good combination of various shapes and good soft magnetic properties indicates the possibility of future development as a new soft magnetic compacted material.

The aim of the present work was to study the influence of mechanical milling and subsequently the compacting on the structure and the soft magnetic properties of NiFe (81 wt. % of Ni) and NiFeMo (79 wt. % of Ni, 19 wt. % of Fe) alloys. We have investigated the influence of powder size on AC and DC magnetic properties of the bulk samples prepared by hot compaction.

Thermal processing of materials in external magnetic field is employed in order to produce a controllable uniaxial anisotropy and to tailor a domain structure in the series of soft magnetic Fe-based alloys. Of particular interest for this work are the advanced silicon steels with low coercivity as well as the soft magnetic FeCo based amorphous/nanocrystalline alloys. The beneficial effects of a heat treatment under magnetic field are discussed in terms of the improved magnetic softness and the possibility to tune the application-oriented properties of these alloys.

Determination of a true temperature and temperature gradient in the solid-state NMR sample is a serious problem in MAS and MAS NMR measurements which use a variable-temperature control unit (VT MAS NMR). In the presented article the method which takes advantage of a temperature dependence of 207Pb NMR chemical shift of Pb(NO3)2 is proposed for the solution of this problem. Dependences of the sample temperature on the MAS rate at room temperature are reported as well as the measured and processed dependences of the sample temperature in the centre and edges of the rotor on the temperature set in the variable-temperature control unit (VT) measured at characteristic (frequently used) MAS rates of 10 kHz and 6kHz, respectively. Analysis of the Pb(NO3)2 spectra provided a maximal temperature gradient in a cylindrical sample as well as the temperature gradient in a narrow region (3 mm) in the centre of the rotor. The results obtained can be used for calculation of the true sample temperature in specific VT MAS NMR experiments and contribute to understanding of principles of frictional heating at axial rotational motion of cylindrical objects in the gas atmosphere.